I have an E71 now and I love it. The size of the phone is amazing with how thin it is. I do really love slide out keyboard phones like the E75 and if I had to choose all over again between the E75 and the E71/72, it would be a touch choice, but I think I would still go with the 71/72 for the thinness. Despite the size of the phone, they keyboard of the E71 is still very good and assuming they didn't change it too much for the 72, you should be in good shape there.

The e72 has a 3.5mm headphone jack which is a big plus for me. 5mp. camera, 600mhz cpu as opposed to the e71's 369mhz, and a new optical navigation key. I was considering the e71, but the 2.5mm headphone jack is a bit of a let down for me. I like to be able to carry 1 device as opposed to a mp3 player and phone, so my phone sees very heavy usage in terms of music, and i have had bad experiences with adapters in the past (original iphone, and e61). Maybe I will just wait for the e72 to come out.